WHEN DO THE DISPENSARIES OPEN? That's unclear. The statute takes effect on January 1, 2013. The law gives the Department of Public Health a period of 120 days (which works out to May 1, 2013) to figure out key questions such as how much pot constitutes a 60-day supply — and, in fact, to determine how it'll run an entire bureaucracy. Which seems, shall we say, optimistic. But that isn't to say it couldn't be done: when Maine voters approved medical marijuana in November 2009, the governor convened a task force within weeks; the task force made recommendations by the following January, and emergency rules were passed in May 2010, approving eight dispensaries.

And if Massachusetts really wanted to expedite its process, it might be able to start in as little as 90 days: that's how long the DPH has to set fees on how much it costs to apply to be a dispensary. Presumably, nobody can apply before, well, the DPH figures out how much it costs to apply. Once it receives an application, the DPH is bound to issue the license within another 90 days — provided the applicant is eligible. So under perfect conditions, it might be theoretically possible for a dispensary to open in less than 180 days — but don't count on it. Until the DPH has its say, it'll be impossible to predict how long it would actually take to construct a dispensary, get its employees registered with DPH as required by law, and grow the marijuana.

HOW MANY DISPENSARIES WILL THERE BE IN MASS? Unclear, though the law appears to put a cap on the number — "up to 35" — that can be opened the first year. The statute is poorly worded, but it seems to want those first 35 dispensaries to be as evenly distributed as possible, with at least one in each Massachusetts county, and no more than five in any one county. The DPH is then empowered to expand "or alter" the number of dispensaries based on demand — opening the possibility that the number could go up, but could also theoretically go down. However, a "hardship provision" elsewhere in the law makes it clear that if there aren't dispensaries within "reasonable" distance of patients, those patients can petition to grow their own weed. The biggest immediate impediment to state-sanctioned dispensaries may be . . . Massachusetts towns. Even before Question 3 passed, north-of-Boston suburbs Wakefield and Reading were planning pre-emptive measures to ban marijuana treatment centers within their borders; Wakefield's town meeting will vote on its ban tonight (November 15).

HOW DOES A DISPENSARY GET ITS WEED? The wording of the law is vague, but there are several references that seem to indicate dispensaries can, and might be required to, grow and cultivate their own supply. In its specific wording, the statute allows dispensary employees immunity to prosecution for "acquiring, possessing, cultivating, processing, transferring, [or] transporting" the drug. The verb "acquiring" would seem to open up the possibility that a dispensary could purchase or import marijuana that it has not grown itself — which raises a number of questions about whether and how growing operations might be maintained separately from dispensaries. Could someone grow medical marijuana legally — as a dispensary's registered agent — and then sell it to the dispensary at a markup? Those are the kinds of decisions that the DPH will have to make early on — and that will have far-reaching consequences for the shape and character of the medical-marijuana industry.